In many fields of medicine, it is necessary to combine two fluids to produce a mixture. For example, it is sometimes necessary during intravenous (IV) therapy to infuse a plurality of liquid medicaments or nutrients into a patient's bloodstream. Mixing the liquids prior to infusion reduces the number of punctures which otherwise would be made in the patient's skin, thereby reducing patient discomfort.
Another instance in which it is desirable to mix two liquids is dental cleaning, during which pressurized water is directed against the patient's teeth to aid in cleaning the teeth. The cleansing water ordinarily impinges against the teeth, and a significant portion of the water then unavoidably splashes away from the teeth and can undesirably contact nearby equipment and the dental technician performing the cleaning. Accordingly, particularly in the era of AIDS, sterilizing the splashed water to reduce the possibility of contaminating medical personnel and equipment with grave diseases becomes a compelling goal. One way to sterilize the cleansing water is to mix it with a sterilization agent prior to directing the water against the patient's teeth.
It is to be appreciated that it is desirable to mix the sterilization agent with the cleansing water in a precise volumetric relationship. In other words, imprecisely injecting the agent into the cleansing water stream can be an inefficient and ineffective way to make the desired mixture. More particularly, injecting too much sterilization agent into the cleansing water can be unpleasant and potentially harmful to the patient, while injecting too little agent into the water can result in ineffective sterilization.
Further, in the case of the dental application discussed above, it is desirable that the mixing of the sterilization agent with the cleansing water be accomplished automatically and continuously as the water is sprayed against the teeth, to reduce the labor intensiveness of the procedure and to avoid encumbering the technician performing the procedure. Moreover, the sterilization agent preferably should be mixed with the cleansing water without requiring extensive modifications to existing dental equipment, and without requiring electrical power and its concomitant costs and potentially interfering power lines.
Accordingly, it is an object of the present invention to provide a dosing device for precisely mixing two liquids. It is another object of the present invention to provide a dosing device for automatically injecting a first liquid into a second liquid stream at an injection rate which is proportional to the mass flow rate of the second liquid. Another object of the present invention is to provide a dosing device that requires no electrical power to function. Yet another object of the present invention is to provide a dosing device which is easy to use and cost-effective to manufacture.